It is known that a pressure distribution sensor utilizes a phenomenon of varying the degree of electromagnetic coupling between two coils depending on the distance between the coils, as disclosed in, e.g., Patent Document 1. In this pressure distribution sensor, a plurality of sensor elements in which a cushion material is placed between coils are arranged in a matrix form to detect the distribution of pressure applied to the sensor elements based on a variation in the degree of electromagnetic coupling. Further, a technique developed by the present inventor and disclosed in Japanese Patent Application Nos. 2005-096580 and 2006-011748 relates to a pressure distribution sensor that has an conductive material disposed adjacent to a plurality of electromagnetically coupled coils and detects the pressure distribution by utilizing a phenomenon of varying the degree of electromagnetic coupling depending on the distance between the conductive material and coils.
Patent Document 1: Japanese Patent Application Kokai Publication No. 2005-156474